An experimental study on the effects of compressive stress on the fatigue crack growth of low-alloy steel

Journal Article · Mon Aug 01 00:00:00 EDT 1994 · Journal of Pressure Vessel Technology; (United States)

DOI:https://doi.org/10.1115/1.2929595· OSTI ID:7156204

Jones, D P; Hoppe, R G ^[1]; Hechmer, J L ^[2]; James, B A ^[3]

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1. Westinghouse Electric Corp., West Mifflin, PA (United States). Bettis Atomic Power Lab.
2. Babcock Wilcox Co., Barberton, OH (United States)
3. Colorado School of Mines, Golden, CO (United States). Metallurgy Dept.

A series of fatigue crack growth rate tests was conducted in order to study the effects of negative stress ratio upon the fatigue crack growth rate of low-alloy steel in air environment. The tests used four-point bend specimens in order to simulate linear stress distributions typical of many pressure vessel applications. This type of testing adds to the knowledge on negative stress ratio effects for low-alloy steels that in the past have been obtained from uniform tension-compression tests. Additionally, the applied bending stress range was varied from low values of applied stress to high values of applied stress over twice the yield strength. Load control was used for tests for which the stress range was less than twice the yield strength and deflection control was used for the higher stress range tests. The crack geometries involved were both short and long fatigue cracks started at notches and tight fatigue cracks for which crack closure could occur over the full crack face. The results are presented in terms of the stress intensity factor ratio R = K[sub MIN]/K[sub MAX]. The negative R-ratio test results were correlated to an equation of the form da/dN = C[[delta]K/(A-R)][sup n] where A, C and n are curve-fitting parameters. It was found that the effects of negative R-ratio on the fatigue crack growth rates for even the high stress range tests could be bounded by correlating the foregoing equation to only positive R-ratio test results and extending the resulting equation into the negative R-ratio regime.

• OSTI ID: 7156204
• Journal Information: Journal of Pressure Vessel Technology; (United States), Vol. 116:3; ISSN 0094-9930
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING
LOW ALLOY STEELS
CRACK PROPAGATION
FATIGUE
PRESSURE VESSELS
EXPERIMENTAL DATA
MECHANICAL TESTS
SERVICE LIFE
ALLOYS
CONTAINERS
DATA
INFORMATION
IRON ALLOYS
IRON BASE ALLOYS
LIFETIME
MATERIALS TESTING
MECHANICAL PROPERTIES
NUMERICAL DATA
STEELS
TESTING
360103* - Metals & Alloys- Mechanical Properties
420200 - Engineering- Facilities
Equipment
& Techniques